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dict.c sub-hashing WIP 2 (try next positions).

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antirez 2016-09-07 17:51:11 +02:00
parent e9ad6b39d8
commit e3aeaa93f2
1 changed files with 45 additions and 12 deletions
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51
src/dict.c
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@ -558,6 +558,18 @@ void dictRelease(dict *d)
zfree(d);
}
void debugDv(dictEntryVector *dv) {
uint32_t entries = dv->used + dv->free;
uint32_t j;
for (j = 0; j < entries; j++) {
unsigned int h2 = (dv->entry[j].hash<<5) + (dv->entry[j].hash>>16);
int target = h2 % entries;
if (dv->entry[j].key == NULL) target = -1;
printf("%d [target=%u]: %s\n", j, target, dv->entry[j].key);
}
}
dictEntry *dictFind(dict *d, const void *key)
{
dictEntryVector *dv;
@ -570,6 +582,8 @@ dictEntry *dictFind(dict *d, const void *key)
idx = h & d->ht[table].sizemask;
dv = d->ht[table].table[idx];
if (dv != NULL) {
// printf("LOOKUP %s\n", key);
// debugDv(dv);
uint32_t entries = dv->used + dv->free;
/* In order to scan less entries, we use the entries vector
* as a sub hash table. The entry is not really guaranteed to
@ -578,7 +592,9 @@ dictEntry *dictFind(dict *d, const void *key)
* we'll succeed in accessing the entry at the first try. */
unsigned int h2 = (h<<5)+(h>>16);
uint32_t j = h2 % entries, i = entries;
// printf("SCAN: ");
while(i--) {
// printf("%d ",j);
dictEntry *he = dv->entry+j;
if (he->key == NULL || he->hash != h) {
j = (j+1) % entries;
@ -590,18 +606,18 @@ dictEntry *dictFind(dict *d, const void *key)
dict_can_resize && /* No copy on write concerns. */
i != entries-1 /* Not already in right place. */)
{
uint32_t destpos = h2 % entries;
uint32_t target_h2 = (dv->entry[destpos].hash << 5) +
/* Try to find a suitable position... */
uint32_t destpos, k;
for (k = 0; k < 3; k++) {
destpos = (h2+k) % entries;
uint32_t target_h2 =
(dv->entry[destpos].hash << 5) +
(dv->entry[destpos].hash >> 16);
// printf("%d -> %d (%d)\n", (int)j, (int)destpos,
// (dv->entry[destpos].key == NULL) ? -1 :
// dv->entry[destpos].hash % entries);
/* Only swap if the entry we are going to replace is
* empty or is not in its final destination. */
if (dv->entry[destpos].key == NULL ||
(target_h2 % entries) != destpos)
{
// printf("From %d to %d\n", (int)j, (int)destpos);
break; /* Valid position found. */
}
if (k != 3) {
dictEntry copy = *he;
dv->entry[j] = dv->entry[destpos];;
dv->entry[destpos] = copy;
@ -609,6 +625,7 @@ dictEntry *dictFind(dict *d, const void *key)
}
}
#endif
// printf("\n\n");
return he;
}
j = (j+1) % entries;
@ -1251,6 +1268,22 @@ int main(int argc, char **argv) {
end_benchmark("Inserting");
assert((long)dictSize(dict) == count);
/* --- */
if (0) {
sds key = sdsfromlonglong(1);
dictFind(dict,key);
dictFind(dict,key);
dictFind(dict,key);
sdsfree(key);
key = sdsfromlonglong(82);
dictFind(dict,key);
dictFind(dict,key);
dictFind(dict,key);
exit(1);
}
/* --- */
/* Wait for rehashing. */
while (dictIsRehashing(dict)) {
dictRehashMilliseconds(dict,100);